


Bella Luna

by sakuplumeria



Series: Love Is a Four Letter Word [3]
Category: Assassination Classroom, Tantei Gakuen Q | Detective Academy Q
Genre: Assassins, Crossdressing, Detective's POV, Detectives, Evening Party, Fluff, Karma is cunning, Kyuu is trying, M/M, Nagisa is accepting, Ryuu is charming, assassin's pov
Language: English
Status: Completed
Published: 2021-01-04
Updated: 2021-01-04
Packaged: 2021-03-14 19:27:29
Rating: Teen And Up Audiences
Warnings: No Archive Warnings Apply
Chapters: 2
Words: 4,325
Publisher: archiveofourown.org
Story URL: https://archiveofourown.org/works/28550856
Author URL: https://archiveofourown.org/users/sakuplumeria/pseuds/sakuplumeria
Summary: Chapter 1: Detective's POVTheir mission was fairly an easy one, to be honest. To get the final and vital evidence for a case they had been working for two months, Kyuu and Ryuu only had to sneak into an evening party and talk with several key persons. That was, until they realized the evening party was for couples.Chapter 2: Assassin's POVKarma would not have guessed that his plan for bringing down a powerful politician could be executed this fast. Turned out that his target was also targeted by two young detectives and he promised to help his accomplices get the vital evidence in a politician's evening party. He was so unwilling to go to another evening-boooring-party at first, but he cunningly turned that into a chance touseNagisa.
Relationships: Akabane Karma/Shiota Nagisa, Amakusa Ryuu/Renjou Kyuu
Series: Love Is a Four Letter Word [3]
Series URL: https://archiveofourown.org/series/2068713
Kudos: 10





	1. Detective's POV

**Author's Note:**

> This time, the fic was inspired by Jason Mraz's [Bella Luna](https://youtu.be/S8WBZLGoSGs), which means Beautiful Moon.
> 
> This is also the first time I try writing a crossover fic, hope you like it and hopefully they are not ooc *finger crossed*

“I think _you_ should go for it, really,” Ryuu looked between dresses.

“Why not just _you_?” Kyuu peered at the line of tuxedos.

“Nah, your voice hasn’t changed like mine so it will be easier for you,” Ryuu turned to look at his partner, “Besides, I’m taller than you.” Ryuu smiled sweetly but somehow it seemed more like a smirk.

Kyuu looked at the violet haired teen and blushed. It was true that Ryuu’s voice had become lower and Kyuu’s had not. It was also true that even though they both gained more height, Kyuu was still half a head shorter than Ryuu. Kyuu finally gave in, “Alright, I’ll do it.”

“Great,” Ryuu took out a black dress from the closet and showed it to Kyuu, “This will look nice on you.”

Kyuu’s flushed face became redder. It was a long dress with long sleeves. Kyuu noticed the side split in front of the right side of the dress and swallowed. Then again, Ryuu must have thought that having a side split would make it easier for him to walk. It was really the best choice of dress if he was to disguise as a woman.

“Y-yeah, I think that will do,” Kyuu agreed in a small voice. Ryuu’s smile got wider as he folded the dress. After taking other things they might need, they left the Special Disguise Room and went to Ryuu’s house to prepare themselves. 

*

Their mission was fairly an easy one, to be honest. To get the final and vital evidence for a case they had been working for two months, Kyuu and Ryuu only had to sneak into an evening party and talk with several key persons. That was, until they realized the evening party was for couples. It was actually a good thing that their accomplice informed them about it, even if it was just hours before the party. It would be very weird and suspicious if they went as both men. They discussed it and concluded that it was not wise to ask Megu or other female students because they would have to brief the case all over and they did not have the time for it. In the end, they decided either one of them would disguise as a woman.

Kyuu was having a hard time dressing up. He was in the middle of wearing the black dress when Ryuu came into the room, all suited up. "Here, let me help you," Ryuu held the back of the dress while Kyuu worked on his fake breasts. They took quite a time but they finally did it. Kyuu was not confident, though. He restlessly looked at himself in the mirror and kept on adjusting his dress here and there.

Ryuu brought the brown wig and helped Kyuu wear it. The wavy brown hair beautifully fell down to just below Kyuu's shoulder. Kyuu looked at the mirror again and blushed harder. He could not believe he could actually look like a girl.

Suddenly, he was aware of two black eyes staring at him. Ryuu's hands held the shorter man's shoulders gently and the lips on the pale face curved up, "You look stunning, Renjou Youko."

"Y-Y-Youko??" Kyuu stuttered.

"Yes, dear Youko, and I believe it is time for us to leave," Ryuu's right hand went down to Kyuu's waist and led his tomato head lover-for-the-night to the car they borrowed from Kazuma.

Of course they were still underage, but since Ryuu proved himself well, DDS granted him special access to a real driving license at the age of 16. It really came in handy, especially for cases like the current one, when their social status—and thus the luxurious car—was needed for the make believe.

Half an hour later, our young detectives stood in front of a grandiose door leading to the grand ballroom, with Ryuu's hand firmly on Kyuu's waist.

Kyuu’s heart was thumping loudly. He felt nervous and he kept twitching his brows. He thought it was because of the disguise, but later he realized that the temperature around them was indeed low. "It's so cold, Ryuu," Kyuu whispered.

Ryuu turned to give a calculating look at his partner. "Oh, let me help you with that," Ryuu's hand slid up and rested on Kyuu's bare back. Kyuu felt the warm hand directly on his skin and his face got pale as he realized, "This dress is _backless_??"

"You really look sexy in it," Ryuu smirked. His hand went back to the waist and pulled the shorter man closer. "It's okay, you'll be fine, Kyuu," Ryuu whispered closely to Kyuu's ear. Kyuu felt Ryuu's breaths and tensed.

Ryuu chuckled seeing the reaction, but he knew they went there for a purpose, so he held himself from further teases. Ryuu let go of Kyuu's waist and offered him his arm. Kyuu got the code and held the arm with both his hands.

Kyuu felt like walking into another world when they got into the ballroom. He had never seen a ballroom that spacious. The ceiling was very high and it had to be supported by gigantic pillars. The glass crystal hanging chandeliers boosted the luxurious and elegant atmosphere.

All the high-class people were chattering and flirting around the room, and all of them wore elegant and expensive suits and dresses. Most of the women wore sexy and skin showing dresses. Maybe Ryuu had chosen him the backless dress so he could blend in with the upper class society better.

As they walked to the center, Kyuu felt many gazes directed towards his handsome partner. Some of the women even winked and made some gestures with their hands. Kyuu instinctively gripped Ryuu's arm tighter and walked closer to the violet haired teen.

Ryuu seemed to ignore all the girls and focused on searching for their accomplice. Upon seeing a redhead, Ryuu held Kyuu's hand with his free hand. "There he is, I'll go there first, okay? Later, Nagisa will approach you and introduce you to those key persons we talked about," Ryuu said casually, as if he was talking about what food they were going to eat.

Kyuu listened carefully and nodded, "Okay, have some fun, Ryuu." He smiled and let go of the arm.

Ryuu quickly turned his face away and walked in the direction of the redhead, but Kyuu still noticed the pink cheeks on his handsome partner and somehow it boosted his own confidence.

"Ryuu, my friend~," the redhead greeted the violet haired teen like a childhood friend, shook the pale hand and bumped to his shoulder.

"Karma," Ryuu greeted him with a polite smile.

"You have some gorgeous companion back there~" Everyone knew Karma's sly and mischievous personality, but Ryuu also knew that he was smart and cunning, making him a highly compatible accomplice.

"Youko’s a bit clumsy, but she is stunning," Ryuu leaned his body to the counter beside Karma.

"Hee~ I hope my Nagisa doesn't overpower him, Nagisa's sweet but deadly," Karma commented in a smug tone.

"Him?" Ryuu could not believe Karma saw right through the disguise, all the more after he addressed Youko as a _she_.

They both paid attention to a light blue haired girl approaching Kyuu. The bluenette was far shorter than Kyuu but there was so much confidence in her overpolite moves. Kyuu looked a bit surprised when greeted by the bluenette, and after a few words, he blushed hard and lowered his head. Ryuu imagined Kyuu would do his signature gestures such as scratching his head or something, and he was not prepared to see this sheepish girly side of the originally black haired. His pale cheeks turned a bit pink following Kyuu's and Nagisa's movements.

"Yep, your lover is definitely a noob, but it's decent for his first try," Karma lifted his glass and drank.

Ryuu was once again amazed and grateful for making Karma their accomplice, not their enemy, "I expect nothing less from you."

"Of course~" Karma's smug voice was back, "Now let's get down to business, shall we?"

*

As Kyuu walked with Nagisa to his first target, he took a peek at his partner who was talking casually with the redhead. Ryuu was always the one who communicated with their accomplice, so this was the first time Kyuu saw the redhead. He was not sure with him, with all the smirks and mischievous faces.

"Don't worry, Karma's like that," the light blue haired girl suddenly said, as if reading Kyuu's mind. "Is he really a politician?" Kyuu asked with a small voice. "He _will_ be, but even in his first year, he already gained a lot of connections," Nagisa smiled sweetly.

Kyuu nodded, so Karma was studying politics or something at the moment. It seemed plausible, and now he was thinking about something else, about Nagisa herself. What relation did Nagisa have with Karma? With his curiosity piqued, Kyuu asked again, "How about you?"

Nagisa looked a bit puzzled at the question, but she still answered, "Well, I'm just helping Karma every now and then." She smiled again and they arrived at their first target.

"Midoriya," Nagisa greeted him with a soft voice.

"Nagisa!” The big man's gaze fell upon the bluenette then to Kyuu, “Who's this?"

"Let me introduce you to Youko…" Nagisa answered. With that, Kyuu's mission started.

After gaining what was needed from all three targets, Kyuu and Nagisa stood beside the desserts' table. Kyuu learned more about the nature of the three key persons from Nagisa while eating macaroons. Throughout the private conversation, Nagisa casually talked as if he was a male, using _boku_ instead of _watashi_. It was bothering Kyuu, actually. The originally black haired could not believe if Nagisa was a male, but at last he gathered his courage to ask.

"You're actually a guy?" Kyuu whispered.

Nagisa sighed. He tried his best to show that he was a _he_ all this time and this brunette still did not believe him. Was he really a detective? "Yes, I am," Nagisa answered firmly.

"But those guys before... They know you- do they know that you're a guy?" Kyuu asked further.

"No," Nagisa's lips made a thin line, "I've disguised a few times and they know me like this."

"Wow, is it because of Karma?" Kyuu made a guess.

Nagisa sighed again, "It's-"

As if having the most sensitive ears, Karma was suddenly there. "What a wonderful conversation, my beautiful ladies," the redhead's smirk was wide and Kyuu could almost see some tiny horns on the redhead. He hooked Nagisa on the waist and stole a kiss from the flushed bluenette.

"Karma," Nagisa gripped the taller man's hand, trying to let himself go, but Karma _was_ stronger so it was a futile effort.

"You look so cute when you're shy, sweetheart~" this time Karma bit Nagisa's ear. Kyuu's face went red seeing the redhead flirting directly in front of his eyes.

Still stunned, Kyuu’s hand was suddenly pulled and he was forced to turn his body to face his assaulter. His lips parted seeing two gleaming but gentle black irises.

"Let's have a dance, Youko," his violet haired prince kissed the back of his hand and Kyuu turned really bright red. Ignoring their accomplices, Ryuu led them to the dance floor and Kyuu could not take his eyes away from the charming prince.

One of Ryuu's hands held Kyuu's and the other gently rested on his waist. Their faces were close enough for Kyuu to feel Ryuu’s breath. One two three, one to three. They fell easily to the triple beats of waltz. Kyuu lowered his head to Ryuu’s shoulder, facing his neck and breathing the masculine scent. He felt so peaceful and excited at the same time.

Ryuu gasped by the tickle from Kyuu’s breaths. His hand on Kyuu’s waist snaked further, pressing their bodies closer. Overwhelmed with excitement, Kyuu unconsciously clutched Ryuu’s chest. Ryuu lowered his head and whispered to Kyuu’s ear breathlessly, “Kyuu, we’re finished here, right? Let’s get back now.”

Kyuu’s whole body jolted in excitement hearing the slightly hoarse voice. “O-okay,” he managed.

Having the permission, Ryuu gracefully led them out from the ballroom. They searched for the redhead and bluenette along the way, but they did not find any trace of them. Well, they could always text them or say something in the next meeting, so they continued to head outside.

As they walked through the garden to the parking lot, Kyuu could not help but notice the bright moon in the night sky. It was a full moon and it shone the garden brilliantly. “Wow, the moon is so beautiful!” Kyuu beamed in awe.

Ryuu turned to look at his partner and suddenly he stopped walking. Kyuu, who was holding hands with him, also stopped. Ryuu’s free hand slid to Kyuu’s cheek and he leaned forward, covering the shorter teen’s lips with his own. Kyuu was surprised at the attack, but he then responded just as hungrily. Soon, their tongue started to spar as they explored their partner's taste. After the need to break the kiss arose, Ryuu watched the tantalizing wet swollen lips on his partner's flushed face.

“Not as beautiful as you,” Ryuu planted a soft butterfly kiss on Kyuu’s nose. “C’mon, now, as much as I want to continue here, it’s really not appropriate,” Ryuu continued with a chuckle.

“Ryuu!” Kyuu blushed hard as he followed his charming prince back to the car.

**Notes for the Chapter:**

> A little trivia, Youko means sunshine or light.


	2. Assassin's POV

Nagisa just arrived at his own apartment when his phone rang. He put his keys on the table and fetched his phone. The screen on his phone was full of red, showing him exactly who was calling.

“Karma.”

“Welcome home, Nagi~”

It still did not sit with him that his best friend knew the fact that he just got home, like literally. Did Karma plant some camera or something in his apartment? That creepy thought sent shivers down his spine.

“What, you’re thinking how I know when you’re home~?”

There was it again, Karma correctly guessing what was in his head. How can the redhead read through his mind so easily? After his first ever big fight with Karma, witnessed by the whole class, Karma had been getting better at reading his mind and emotions. And it just kept getting better as they grew older, even though they did not meet as much anymore. It must be because it was _Karma,_ the bluenette concluded. He sighed and smiled.

“What is it, Karma?”

“Getting right to business, aren’t you?”

“...”

“Are you free tonight?”

“Another party?”

“Let’s just see~ Six at my place?”

“Can I really say no?”

*

Karma opened the passenger door and escorted Nagisa out of his red lamborghini. As usual, the short male held the taller’s arm as they walked through the beautiful luxurious garden. He also noticed how the redhead slowed his pace to accommodate their walk pace.

Nagisa could not help it, he was once again wearing a dress. At least, the sleeveless blue dress had a side split, making it easier for him to walk. Yet, it was the first time he wore a low v cut dress. The bluenette unconsciously hid his face a little by the thought. Karma, of course, noticed it.

The redhead wrapped his hands around the small figure and studied his lovely friend keenly. A naughty smirk appeared on his already mischievous face. One hand slid up to caress the bluenette’s cheek, “What is it?” The hand sensuously slid down to the bare skin on his chest, “You’re afraid of being too sexy~?”

Nagisa’s breath hitched at the touch and his hand moved fast to grip Karma’s wrist, stopping the movements further.

“Hee~ You’re as eager as always,” Karma ducked his head and his smirk turned into a vicious grin.

“Karma,” Nagisa’s fierce bright blue eyes looked straight up to fiery golden ones.

Karma loved those bloodlusted eyes the best. His spirit burnt within his body and he could not stop the want to pin the bluenette and have him right there right then.

However, as annoying as it could be, the image of his ridiculous yellow ex-teacher suddenly showed up in his mind, reminding him to lower his overflowing energy and desire and focus on the mission on hand. Karma finally gave his desire up and burst in laughter, “Okay, okay, my queen, I’ll stop.” Nagisa loosened his grip and his eyes lost its bloodlust. Well, he could always have him another time, Karma thought.

“So, just to make sure. You’ll meet up with this violet haired guy, Ryuu or something, while I meet his partner and introduce him to Midoriya?” Nagisa reviewed the plan after they went into the grandiose ballroom.

“~and also Matou and Gato,” Karma added. “You can hear me through the earpiece, can’t you?”

“Loud and clear,” Nagisa answered with his signature smile.

Karma blushed a little at that, “Okay, I’ll tell you when they arrive.”

Nagisa nodded and went around the room while Karma took a drink from a counter.

Soon, the so-called detective Ryuu and his partner got into the room. Karma almost choked by the sight. Ryuu was definitely a charming prince, but his partner... was definitely a _he_ . And while _his_ disguise was quite okay, it was just way below Nagisa’s. Nagisa was a natural, Karma concluded. Well, the bluenette was always thought of as a girl even way before he started to deliberately disguise himself.

“The food looks delicious~” Karma spoke to no one.

“If you’re not that evil, you could’ve been more popular than this violet guy,” Nagisa’s voice was cute despite the slight distortion from the earpiece.

Karma laughed heartily. “I’ll take that as a compliment,” he whispered.

Soon, the mentioned violet haired man approached him. "Ryuu, my friend~," Karma greeted his guest like a childhood friend, shook the offered hand and bumped his shoulder against the shorter male.

"Karma," Ryuu greeted him with a polite smile. Karma noticed that even though the detectives were a few years younger than him, they really had what it takes to communicate with adults, to be elegant and polite. Especially this violet haired guy.

"You have some gorgeous companion back there~" Karma directed his gaze to the disguised brunette.

"Youko is a bit clumsy, but she is stunning," Ryuu leaned his body to the counter beside Karma.

"Hee~ I hope my Nagisa doesn't overpower him, Nagisa's sweet but deadly," Karma commented casually.

" _Him_?" Ryuu’s eyes went wide.

Karma grinned wider at the reaction. "Yep, your lover is definitely a noob, but it's decent for his first try," he lifted his glass and drank.

Ryuu studied the redhead closely and nodded at last, "I expect nothing less from you."

"Of course~" Karma learned about teamwork in his last year of junior high school. Even though he was confident he could take down the politicians he was targeting, he was surprisingly pleased when Ryuu reached out to him a month ago. The young detective and his partner were in the middle of investigating his target, so Karma used the chance to use them to bring down his targets. Even though his detective friends were young, their aura showed that they were indeed experienced detectives. In only a month, they were this close and soon the case would be closed. Karma was satisfied with the collaboration and he already listed them down for pairing if the need arose one day. "Now let's get down to business, shall we?"

*

“Hey,” Nagisa poked the detective in disguise.

The brunette detective twitched a little before turning to face him. “U-Uh, hello, are you Nagisa?”

“Yes, nice to meet you,” Nagisa smiled, “How should I call you?”

“I-I’m Youko, nice to meet you too,” Youko answered sheepishly.

Nagisa had a feeling that this detective was a male, and he was sure of it now. “Um, I’m sorry but your real hair is showing near your right ear,” he said in a low volume.

Youko’s face suddenly turned bright red. She, _he,_ lowered his head as he fixed his hair, “Thanks for that. It’s my first disguising and I’m glad you save me from getting caught.”

“My pleasure,” Nagisa smiled, “Now let me introduce you to some people.”

After being introduced to three politicians, Nagisa led Youko to the desserts table. “I heard from Karma that Midoriya uses his connections to the media to twist people’s opinion, like for the latest news of the embezzlement in the Midori Capital,” Nagisa saw confusion in the brunette’s face for some time now, and he was trying to find topics to ease the detective. It seemed that this information was also not what was bothering the brunette’s mind.

Nagisa was saved from further assumptions because Youko suddenly whispered, "You're actually a guy?"

So, _that_ was what was on the brunette’s mind? Nagisa did address himself as a male, using _boku_ instead of _watashi_ , when talking to the detective. He sighed and answered with a smile, "Yes, I am."

"But those guys before... They know you- do they know that you're a guy?" Youko asked again.

"No," Nagisa's lips made a thin line, "I've disguised a few times and they know me like this."

"Wow, is it because of Karma?" The detective made a good guess.

Nagisa sighed again, "It's-"

As if having the most sensitive ears, the mentioned redhead was suddenly there. "What a wonderful conversation, my beautiful ladies," Karma smirked widely as he hooked Nagisa on the waist. He ducked his head and stole a kiss from the flushed bluenette.

"Karma," Nagisa gripped the taller man's hand, trying to let himself go, but the taller male was stronger. Such a futile effort.

"You look so cute when you're shy, sweetheart~" this time the redhead bit his ear. From the corner of his eyes, Nagisa could look at the flustered face of his new detective friend. His attention was forced to his lover again as Karma went down to his neck where he bit his sensitive spot.

“K-Karma,” Nagisa cursed himself for his raspy voice. He knew it was one of Karma’s turn on.

“Mmm~,” Karma’s lips went back to his ear, “We should find a better place.”

That was all the warning Nagisa got before Karma pulled him by the waist to the side of the room. The ballroom was so spacious that it had to be supported by abnormally large pillars, and Karma was leading him to the back of one of them. Still, Nagisa could not process the thought of Karma actually pushing him _into_ one of the huge pillars.

After adjusting his eyes, Nagisa realized there were luminous red sticks attached to the dark circular room. The next thing he was aware of was the cool atmosphere in the tight small space. There were apparently small ventilation holes in some direction. However, the most intense feeling was the heat from the body pressed to him, pinning him.

“How do you like my secret room?” Karma asked in a hoarse whisper.

“Y-you seriously made this?” Nagisa answered with the same volume.

“Mm~hmm, glad I finished it last night,” Karma’s fingers brought the bluenette’s chin up.

Nagisa met Karma’s gleaming eyes. The red light made the golden irises seem like literal burning fire. Nagisa exhaled, “Unbelievable.”

Karma’s hands made their way to his hips and suddenly Nagisa was on the air. The bluenette instinctively gripped Karma’s suit and his head jerked up, “Kar-”

Whatever protest he was uttering was silenced by hungry lips. Nagisa was definitely not one who would back down from challenges, so he protested with his deathly kiss instead. Karma took up the challenge with his fierce kiss. Their lips, tongues, and even teeths were all tangled up in the battle.

Karma moved his leg between Nagisa’s gracefully through the side split, effectively fixing the proportioned height. His hand then slid between their bodies and found the bare skin above the bluenette’s navel. Nagisa could not help a loud moan escaping his mouth.

Karma broke the kiss and went down to Nagisa’s neck, “This secret room is perfectly camouflaged, but I do not make it soundproof, you know?” He licked a sensitive spot and was rewarded with a gasp, “I don’t mind listening to your sexy voice, but do you really want others to find us so quickly~?”

Nagisa pushed _down_ Karma’s shoulders in an attempt to move the redhead from his neck. “Karma!” He whispered between heavy breaths.

“O~h? Okay~”

Nagisa’s eyes went wide. Unfortunately for him, this kind of voice meant Karma was misunderstanding him on purpose.

With ease, Karma put Nagisa down and then knelt before him.

 _No, no, no, this is not good,_ Nagisa was horrified with the new position.

The redhead looked up to him, his eyes were now cognac brown, “You’re right~ It's time for my main course.”

*

♥

*

For once, Nagisa was glad that Karma's strong hand was on his waist, firmly leading him through the crowds as he thrived to walk normally. His head was spinning by the bright lights after the very steamy make out in the dark room.

Karma was unusually searching for something or someone, Nagisa realized. Probably the young detectives. As if hearing his thought, Karma spoke up, "They're gone. Probably they continue their night elsewhere."

Nagisa felt the redhead's breath against his ear as he whispered, "Should we too~?"

Red colors found their way up the bluenette's face once again. Nagisa was trying to reply to the teasing but before he could do it, Karma fastened his pace and half carried the bluenette in the air. Deep in his heart, Nagisa knew he would not stand a chance to change Karma's mind at that point, so with his signature smile, he elegantly followed the pace.

Besides, it's just Karma, his most trusted best friend, or was he? Who he hung out with more frequently than his other ex-classmates. Who he possibly did many unusual-things-you-should-not-do-with-a-friend with… What could possibly go wrong?


End file.
